The meeting, the first such high-level confab between the nations in five years, was appropriate considering the two have more in common than just a love of noodles. But can the Loach and Super Mario save the day from debts and deficits?

Both leaders have to battle a mountain of public debt amid lackluster economies and pension systems sagging under aging populations.

Though it may have been a bit impolite for a guest, Mr. Monti in a speech Wednesday suggested that his host had far bigger problems than he did.

“If we aggregate the deficits and the debts of all the 17 euro zone member states, we come up with an aggregate deficit to GDP and debt to GDP ratio that is considerably lower than is the case for the U.S. or the U.K. or Japan,” he said, adding that the euro zone was much more fiscally “virtuous.”

Markets, however, may beg to differ. While the yield on 10-year government bonds in Italy has fallen from over 7.5% last fall, it still remains relatively high, at 5%. Yields on similar bonds in Japan are near 1%. Since bond yields are an indicator of their holders’ confidence in the country’s ability to pay back its debts, that suggests investors trust Japan more, despite its higher load.

Japan is also less beholden to the whims of fickle foreign investors than Italy. Foreign ownership of Japan’s government debt was 8.5% at the end of 2011 according to the Bank of Japan. In Italy, that number is about 50%. And, in a pinch, Tokyo can rely more on its central bank. The Bank of Japan can always print money to pay off debt (though its leaders vow never to do so). But since the power to print euros lies in the hands of the European Central Bank, that option’s not open to Italy.

On the other hand, Mr. Monti appears to have more political capital, and clout, than Mr. Noda. The Italian leader became the head of a cabinet of nonelected officials last November with the caveat that he would not run in next spring’s elections after pushing through fiscal reforms. Mr. Noda’s increasingly fragile government faces prospects of an imminent election if his ruling party fractures over the tax issue.

Even after presenting controversial proposals for labor reform to Parliament, Mr. Monti cinched a 55% approval rating in March, according to a Rome-based polling company (in Italian). That’s a figure that Mr. Noda could definitely envy given his current 34% rate.

About Japan Real Time

Japan Real Time is a newsy, concise guide to what works, what doesn’t and why in the one-time poster child for Asian development, as it struggles to keep pace with faster-growing neighbors while competing with Europe for Michelin-rated restaurants. Drawing on the expertise of The Wall Street Journal and Dow Jones Newswires, the site provides an inside track on business, politics and lifestyle in Japan as it comes to terms with being overtaken by China as the world’s second-biggest economy. You can contact the editors at japanrealtime@wsj.com